String optionalOnPrimitive(@DelegatesTo(value = OptionalOnPrimitive, strategy = Closure.DELEGATE_FIRST) Closure<?> spec = {}) {
        OptionalOnPrimitive config = optionalOnPrimitiveConfig(spec)
        config.render()
    }

    OptionalOnPrimitive optionalOnPrimitiveConfig(@DelegatesTo(value = OptionalOnPrimitive, strategy = Closure.DELEGATE_FIRST) Closure<?> spec) {

                }

                @TaskAction public void execute() {}
            }
        """

        expect:
        assertValidationFailsWith([
            error(optionalOnPrimitiveConfig {
                type('MyTask').property('primitive')
                    .primitive(primitiveType)
            }, "validation_problems", "cannot_use_optional_on_primitive_types"),
        ])

        and: